Kinetics ofIn VitroLysozyme Deposition on Silicone Hydrogel, PMMA, and FDA Groups I, II, and IV Contact Lens Materials

Abstract

We sought to compare the kinetics of in vitro lysozyme deposition on silicone hydrogel (SH), polymethyl methacrylate (PMMA), and FDA groups I, II, and IV contact lenses. Lenses were incubated in 125I-labeled lysozyme for time periods ranging from 1 hr to 28 days, and radioactive counts were determined. SH lenses and PMMA deposited less lysozyme than conventional hydrogel lenses (p < 0.05). Lysozyme accumulation on group IV lenses reached a maximum on the seventh day and then plateaued, whereas on groups I, II, and SH lenses, deposition continued to increase across all time periods, reiterating that kinetics of lysozyme deposition is highly material dependent.

Quartz crystal microbalance study of protein adsorption kinetics on poly(2-hydroxyethyl methacrylate)

“…However, given that we are using a hydrophilic substrate, with relatively high concentrations, and the first couple data points may be affected by the protein solution being injected, we see no evidence for either of these effects. The second constant τ 2 corresponds to a slower increase in effective mass, the size of which suggests that this is simply continued adsorption of multilayers as Subbaraman et al [56] see increases in adsorption up to at least 28 days. However, the continued adsorption may still depend on a slow denaturing, or rearrangement of already adsorbed lysozyme to allow more to adsorb.…”

Impact of Ethylene Oxide Butylene Oxide Copolymers on the Composition and Friction of Silicone Hydrogel Surfaces

“…Unlike conventional poly(2-hydroxyethyl methacrylate)-, or pHEMA-, based hydrogel lenses, which rely on water for oxygen transport [2,3], SH lenses achieve high oxygen permeability through the incorporation of modified siloxane monomers [4]. This characteristic has allowed these lenses to be used for overnight extended wear with significantly reduced corneal hypoxia [5].…”

“…Together, the results demonstrate close correlations between the surface chemistry and frictional response of the lens systems, as well as the opportunity for solution-based modification of SH lenses. Table 1 [4,14]. Prior to analysis or solution treatment, all lenses were soaked in a standard buffered saline solution (Unisol Ò 4, Alcon, Fort Worth, TX) for at least 24 h. This procedure was necessary to remove residual components of packing solutions from the hydrogel surface [22,23].…”

“…Details of the three major SH contact lenses with their respective treatment for improving hydrophilicity[4,10] NVP N-vinyl pyrrolidone, TPVC tris-(trimethylsiloxysilyl) propylvinyl carbamate, NVA N-vinyl amino acid, PBVC poly(dimethysiloxy) di(silylbutanol) bis(vinyl carbamate), mPDMS monofunctional poly(dimethylsiloxane), PVP poly(vinylpyrrolidone), TRIS trimethylsiloxy silane, DMA N,N-dimethylacrylamide, HEMA poly(2-hydroxyethyl methacrylate)…”

Lysozyme transport in p-HEMA hydrogel contact lenses

“…Group I lenses are non-ionic with low water content, group II lenses are non-ionic with high water content, group III lenses are ionic with low water content and group IV lenses are ionic with high water content. It is widely accepted that group IV Etafilcon lenses, i.e., p-HEMA with copolymer methacrylic acid (MA), deposit substantially more lysozyme than all other hydrogel lens materials [1,2,[4][5][6]10,11]. Higher water content and electrostatic interactions between lysozyme and the negatively charged MA likely drive the large uptake of lysozyme by the group IV lenses.…”